Method of producing ferrous sheet material



Patented Aug. 29, 1939 UNITED STATES METHOD OF PRODUCING FE-RRO-US SHEETMATERIAL Alfred J. Castle, Chicago, Ill., assignor to Inland SteelCompany, Chicago, 111., a corporation of Delaware No Drawing.Application October 26, 1936, Serial No. 107,735

11 Claims.

My invention relates more particularly to the production of ferroussheet material, especially cold reduced sheet material, or sheet metal,coated, as for example by molten tin; as in the case of the productionof tin-plate, or terne.

The invention furthermore has to do with the production of such materialprovided in sheet form of relatively light gage, viz., of about 30 gageor lighter.

One of my objects is to provide improvements in the production of coldreduced ferrous material of relatively light gage, to the end that flatsheet material having the desired rigidity or stiffness to preventfluting and stretcher strains, in

- forming the material to shape,may be produced more economically, andby less expensive equipment, than hitherto possible.

Another object is to provide for the production of a flatter coldreduced ferrous sheet of relatively light gage than has hitherto beenpossible;

and other objects as will be manifest from the following description.

My novel method involves the skin rolling, after annealing, of coldreduced sheet material with rolls the working surfaces of which are dullor rough, as distinguished from the smooth bright surfaces of what arecommonly known in the metal rolling art as bright or smooth rolls, toeffect a substantial portion, preferably the major portion, of the fullreduction to which the sheet material is to be subjected after theannealing operation referred to; the sheet material, thus rolled andwith the opposite faces thereof thereby dulled or rbughened, being thenrolled, in the production of smooth coated material, on rolls theworking faces of 'which are smooth, with the result of smoothing theroughened surfaces of the sheet material sufficiently to permit of thedesired smooth and even application, in a well known manner, of thedesired coating material, as for example tin, or terne, in moltencondition, to the surfaces of the sheet material.

As a specific example of procedure'within my invention the following maybe cited, but without any intention of limiting the invention thereto.

Hot rolled strip material, such as steel, from which the finished sheetsare to be produced is cold reduced from the hot band-size at least abouton a tandem mill in accordance with common practice, to about 30 gage orlighter, as desired, and within about 1 to about 5% of the gage desiredof the finished sheets, the sheet material in this operation beingrolled into relatively long wide strip sheet form of light gage. Thematerial thus cold reduced is wound into a coil (CI. 29-18) v and incoil form is subjected to an annealing operation, preferably thorough aswill be understood by those skilled in the art and in accordance withthe common practice of manufacturing tin plate, namely, subjected tosuch heat and 5 for such length of time as to cause all portions of thesheet material to become completely annealed and render the material ofmaximum softness throughout. The annealed material is then passed, inuncoiled, but in strip sheet condition, 10 through a pair of dullsurfaced skin rolls referred to in dry condition which operate to effecta substantial portion of the above-referred-to about 1 toabout 5%reduction of gage of the cold reduced sheet material, preferably toeffect the major portion of the about l to about 5% reduction abovestated even up to about 85% of the total reduction desired afterannealing, and cause the opposite surfaces of the sheet material to beroughened or dulled; these dull surfaced skin rolls being providedpreferably as the working rolls of a mill of the 4-high type. Theskinrolled sheet material is then passed through the smooth surfacedrolls, referred to, which are in dry condition, primarily for thepurpose of rolling the rough surfaces of the sheet material intosufliciently smooth condition as to permit of application of the metalcoating smoothly and uniformly to the sheet surfaces. Such smoothrolling of the material involves the reduction of the sheet material bythe smooth rolls to an amount sufficient to cause the sum total of thereduction by the rough rolls and the smooth rolls to equal that desired,via, about 1 to about 5% in the example given; and to the extent thatthe sheet material'is reduced, amounts to a skin rolling operationsupplementing that performed by the dull surfaced rolls. The sheetmaterial is then cut into the desired sheet lengths; pickled as bysulfuric acid in accordance with common practice; and then coated withthe desired metal, as for example molten tin, to form tin-plate, inaccordance with common practice; the reduction given in the skin-rollingof thematerial' being of such amount asstated. as to ,ensure the ntioninthe'flnlshedm'etal coated sheet material after subjection to thetemperature used 'intlie applycoated sheet material sufficiently rigidto avoid fiuting-when bent as for example in the forming of can bodiesand to avoidstretcher strains as for example in can tops and bottoms asby drawing; and by rolling the roughened sheet material in a mill havingsmooth working rolls the roughened condition of the sheet material maybe reduced to the extent desired, while the roughened surfaces of thematerial allow for uniform reduction thereof which insures theproduction of fiat sheets.

As will be understood, however, the percentage of reductions obtained bythe rough rolls and the smooth rolls may be varied from that describedto the end that the combined amounts of reduction'obtained by the roughrolls and the smooth rolls serve to render the finished metal coatedsheet material sufliciently rigid to avoid fiuting and stretcher strainsin the forming of the finished material to shape, and result in theproduction of fiat sheets.

Any suitable dull or rough surfaced rolls may i be employed for the dullor rough rolling of the sheet material as described. By way of example,metal rolls, preferably hardened steel rolls, of at least 70 scleroscopehardness blasted with abrasive particles, as for example sand or steelgrit, to roughen the working surfaces of the rolls,

may be employed. When the abrading particles used are steel grit, therolls, if of scleroscope, or higher, by way of example, would be firstblasted throughout their working surfaces by steel grit of about 30mesh, followed by the blasting of the rolls throughout their workingsurface with steel grit of about 50 mesh. In the example given, one mayemploy air pressure of about 55 pounds to 65 pounds per square inch inblasting with 30 mesh grit, 60 pounds pressure being quite suitable; andin the subsequent blasting with 50 mesh grit, the pressure may, forexample, be from 65 pounds to '70 pounds per square inch. For rolls ofabout 70 scleroscope, the blasting may be done simply with 50 mesh grit,at a pressure of 50 pounds to 60 pounds, preferably about 55 pounds.

While rolls of a scleroscope hardness of over 70 are mentioned above,the invention is not limited thereto as certain advantages of theinvention may be availed of by the .use of metal rolls of lessscleroscope hardness than that referred to. I

By the improved method, it is possible to attain the necessary reduction(subsequent to annealing) by a single pass through a pair of roughrolls, followed by a single pass through a pair of smooth rolls,--asuflicient reduction to insure the requisite temper in the sheetmetalafter it has been passed through the molten coating bath.

While I have described a particular procedure in practicing my novelmethod I do not wish to be understood as intending to limit my inventionthereto as the same may be variously modified and altered withoutdeparting from my invention, it being my intention to claim my inventionas fully and completely as the state of the artwill permit. As anexample of a further modification of the method the sheet materialinstead of being cut to sheet lengths after the smooth roll rollingoperation as above described may be cut to sheet lengths either aftercold reduction and before annealing of after annealing and before roughskin-rolling, but preferably after cold reduction and before annealing,in the former case permitting the sheets to be annealed in stackcondition; and the rolling with dull or rough rolls and subsequentlywith smooth rolls, as above referred to, performed on the separatesheets instead of on the sheet material in strip sheet form.

What I claim as new, and desire to secure by Letters Patent, is:

1. The method of producing cold reduced ferrous sheet material to becoated with a metal coating which comprises cold rolling ferrousmaterial to a gage approximating the final gage of the finishedmaterial, annealing the cold reduced material, skin rolling the annealedma terial on rough surfaced rolls, and rolling the skin-rolled materialon smooth surfaced rolls.

2. The method of producing cold reduced ferrous sheet material to becoated with a metal coating which comprises cold rolling ferrousmaterial .to a gage approximating the final gage of the finishedmaterial, annealing the cold reduced material, skin rolling the annealedmaterial on rough surfaced rolls to reduce it about 1%% to about 4%%,and rolling the skin-rolled material on smooth surfaced rolls.

3. The method of producing cold reduced ferrous sheet material to becoated with a metal coating which comprises cold rolling ferrous stripmaterial to about 30 gage or lighter, annealing the cold reducedmaterial, skin rolling the annealed material on rough surfaced rolls,and rolling the skin-rolled material on smooth surfaced rolls.

t. The method of producing cold reduced ferrous sheet material to becoated with a metal coating which comprises cold rolling ferrous stripmaterial into long strip sheet form to a gage approximating the finalgage of the finished material, coiling the material, annealing the coldreduced material in coil form, skin rolling the annealed material inuncoiled condition and in strip sheet form on rough surfaced rolls, androlling the skin-rolled material on smooth surfaced rolls,

5. The method of producing cold reduced ferrous sheet material to becoated with a metal coating which comprises cold rolling ferrous stripmaterial into long strip sheet form of approximately 30 gage or lighter,coiling the material, annealing the cold reduced material in coil form,

skin rolling the annealed material in uncoiled condition and in stripsheet form on rough surfaced rolls, and rolling the skin rolled materialon smooth surfaced rolls.

6. The method of producing cold reduced ferrous sheet material to becoated with ametal coating which comprises cold rolling ferrousmaterialto a gage approximating the final gage of the finished material,annealing the cold reduced material, skin rolling on rough surfacedrolls the annealed material cut to sheet length, and rolling theskin-rolled sheets on smooth surfaced rolls.

7. The method of producing cold reduced ferrous sheet material to becoated with a metal coating which comprises cold rolling ferrous stripmaterial into long strip sheet form to about 30 gage or lighter,annealing the cold reduced material, skin rolling on rough surfacedrolls the annealed material cut to sheet length, and rolling rolls, androlling the skinc-rolled'sheets on smooth surfaced rolls.

9. The method of producing cold reduced ferrous sheet material to becoated with a metal coating which comprises cold rolling ferrousmaterial to a gage approximating the final gage of the finishedmaterial, annealing the cold reduced material, cutting the annealedmaterial into sheets, skin rolling the sheets on rough surfaced rolls,and rolling the skin-rolled sheets on smooth surfaced rolls. A

10. The method of producing cold reduced ferrous sheet material to becoated with a metal coating which comprises cold rolling ferrous stripmaterialinto long strip sheet form to about 30 gage or lighter,annealing the cold reduced material, cutting the annealed material intosheets. skin rolling the sheets on rough surfaced rolls, and rolling theskin-rolled sheets on smooth surfaced rolls. v

11. The method of producing cold reduced ferrous sheet material to becoated with a metal coating which comprises cold rolling ferrousmaterial to a gage approximating the final gage of the tinishedmaterial, annealing the cold reduted material, skin rolling the annealedmaterial on rough surfaced rolls, and rolling the skin-rolled materialon smooth surfaced rolls, with a reduction of the material by the smoothsurfaced rolls materially less than the reduction by the rough surfacedrolls.

ALFRED J. CASTLE.

